Behavior of lactating rats in a dual-chambered maternity cage

Videotape sampling of behavior in a dual-chambered apparatus indicates that the continuous monitoring of the amount of time a mother spends in the cage with its litter can be taken as a valid reflection of maternal behavior. Nursing is the principal behavior of lactating females while in the compartment with their litters; lying still, consummatory behavior, and activity occur with greater frequency in the cage away from the litter. Both the time that mothers spend with their litters and nursing behavior displayed a 24-hr rhythm with crest values occurring during the period of light.     

Structure fine du rein de l'Epinoche (Gasterosteus aculeatus L.) au cours de sa transformation muqueuse

Résumé Pendant la période de reproduction, les néphrons du rein de l'Epinoche mâle subissent d'importantes modifications de structure sous l'action des hormones sexuelles. Au niveau de chacun d'entre eux, se différencient deux segments distincts par leur fonction et par leur cytologie. Le segment urinaire, très court, est formé de cellules identiques à celles du jeune, qui remplissent leur fonction d'excrétion. Le segment glandulaire, plus volumineux, subit une transformation muqueuse et élabore une sécrétion qui sert à construire le nid. L'évolution de ces deux segments est étudiée au cours de la période de reproduction et les modifications cytologiques correspondantes sont décrites.

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Fine structure of the kidney of the three-spined-stickleback (Gasterosteus aculeate L.) during its mucous transformation

Summary Under the action of sexual hormones the nephrons of the kidney of the male three-spined-stickleback undergo considerable transformations during the breeding period. They differentiate into two segments which differ from one another in function and cytology. The cells of the urinary segment are identical to those of the young fish. They have an excretory function. The glandular segment undergoes a mucous transformation and synthesizes a secretion which is used for the building of the nest. The cytological transformations occuring at the level of these two segments during the breeding period are described with special attention to the mucous cells.

     

Second virial coefficient of alpha-crystallin

Light scattering studies were performed on bovine alpha-crystallin measuring the scattering intensities as a function of scattering angle, concentration, and temperature. The data yielded the molecular weight, radius of gyration, and second virial coefficient of alpha-crystallin at different temperatures. The second virial coefficient increased with increasing temperature. Both the enthalpy and entropy of solution of alpha-crystallin are positive. The Flory theta temperature was found to be 271 K.     

Body shape and differences between species

The variation of body shape among prosimians is reviewed. Special emphasis is placed on the selective advantages, that is the mechanical reasons, to which variants of the locomotor apparatus can be traced back. There are differences found in the cheiridia, but at present they cannot be explained in terms of mechanics; there is nearly no knowledge about the mechanical meaning of their diversity. Myological characteristics of taxa can be explained mechanically, but this has not yet been done. Well known are variations of body proportions. These discriminate higher taxa, and are largely coincident with the often-used locomotor categories. In spite of this, there are only few sound arguments about the real biomechanic value of characteristic proportions for a given locomotor mode. What is known on this field, is reviewed. Progress can be made only, if the mechanical conditions, set by postural behavior and locomotion, are understood completely. The subtle distinctions between lower taxonomic units can normally be identified only on the basis of detailed and quantified analyses of movements on one hand, and of biometrics on the other. In the few cases in which such studies have been made, the differences of morphology fit to the mechanical requirements of locomotion which also differ only in quantitative details.     

Symbiotic effectiveness of Bradyrhizobium strains isolated from Parasponia and tropical legumes on Parasponia host species

The symbiotic effectiveness of Bradyrhizobium strains isolated from three species of Parasponia and from legumes were compared on Parasponia grown in Leonard-jars. Effectiveness of each symbiotic association was estimated from dry weight and total nitrogen of shoots and nodules of plants grown on medium free of combined nitrogen. Twenty strains isolated from three species of Parasponia were found to vary in their effectiveness on P. andersonii, the least effective fixing one fifth of the nitrogen of the most effective strains. The outcome of the symbiosis was not associated with the host source of the test strain. P. andersonii, P. rugosa and P. rigida responded differently to a selection of seven strains of Parasponia Bradyrhizobium; some strains were either ineffective or fully effective on each host, while others varied in their symbiotic performance. P. andersonii fixed significantly (P < 0.001) larger quantities of nitrogen than either P. rugosa or P. rigida with p. rigida being the least effective. In contrast to Bradyrhizobium strains from Parasponia spp. which formed nodules rapidly (within 11–20 days), nine strains isolated from legumes required between 25 and 74 days to form partially effective nodules. The thre Parasponia species formed relatively large quantities of nodule tissue relative to the amount of nitrogen fixed and shoot dry matter produced. The Bradyrhizobium isolated from Parasponia plants growing in Papua New Guinea soils could be grouped together on the basis of their infection characteristics on Parasponia and legumes.     

Coaction of blue/ultraviolet-A light and light absorbed by phytochrome in controlling growth of pine (Pinus sylestris L.) seedlings

Photomorphogenesis is a conspicuous feature in conifers. In the case of the shade-intolerant Scots pine (Pinus sylvestris L.), control of stem growth by light is well expressed at the seedling stage and can readily be studied. The present data show that hypocotyl growth is controlled by the far-red-absorbing form of phytochrome (Pfr). However, the Scots pine seedling requires blue or ultraviolet (UV-A) light to become fully responsive to Pfr. Blue/UV-A light has no direct effect on hypocotyl growth and its action appears to be limited to establishing the responsiveness of the seedling to Pfr. This type of coaction between phytochrome and blue/UV-A light has been observed previously in a number of angiosperm seedlings. With regard to the high irradiance reaction of phytochrome in long-term far-red light the pine seedling deviates totally from what has been observed in etiolated angiosperms since continuous far-red light has no effect on stem growth.Abbreviations B light of wavelength between 500 and 400 nm - FR standard far-red light - HIR high irradiance reaction of phytochrome - R high-fluence-rate red light (_R = 0.8) - RG9-light long-wavelength far-red light defined by the properties of the Schott RG9 glass filter (_RG₉<0.01) - = Pfr/Ptot wavelength-dependent photoequilibrium of the phytochrome system (far-red-absorbing form of phytochrome/total phytochrome) - UV-A near ultraviolet light of wavelength between 400 and 320 nm - W white light Research supported by a grant from the Deutsche Forschungsgemeinschaft (Schwerpunkt Physiologie der Bäume).